With the introduction of the Intel Kaby Lake processors and Intel Z270 chipset, unprecedented overclocking became the norm. The new processors easily hit a core speed of 5.0GHz with little more than CPU core voltage tweaking. This overclocking performance increase came with a price tag. The Kaby Lake processor runs significantly hotter than previous generation processors, a seeming reversal in temperature trends from previous generation Intel CPUs. At stock settings, the individual cores in the CPU were recording in testing at hitting up to 65C - and that's with a high performance water loop cooling the processor. Per reports from various enthusiasts sites, Intel used inferior TIM (thermal interface material) in between the CPU die and underside of the CPU heat spreader, leading to increased temperatures when compared with previous CPU generations (in particular Skylake). This temperature increase did not affect overclocking much since the CPU will hit 5.0GHz speed easily, but does impact the means necessary to hit those performance levels.
Like with the previous generation Haswell CPUs, a few of the more adventurous enthusiasts used known methods in an attempt to address the heat concerns of the Kaby Lake processor be delidding the processor. Unlike in the initial days of the Haswell processor, the delidding process is much more stream-lined with the availability of delidding kits from several vendors. The delidding process still involves physically removing the heat spreader from the CPU, and exposing the CPU die. However, instead of cooling the die directly, the "safer" approach is to clean the die and underside of the heat spreader, apply new TIM (thermal interface material), and re-affix the heat spreader to the CPU. Going this route instead of direct-die cooling is considered safer because no additional or exotic support mechanisms are needed to keep the CPU cooler from crushing your precious die. However, calling it safe is a bit of an over-statement, you are physically separating the heat spreader from the CPU surface and voiding your CPU warranty at the same time. Although if that was a concern, you probably wouldn't be reading this article in the first place.